need help to start tuning my z24

[white Z24]

I have a 2001 cavalier z24 with aem intake, pacesetter 4-1 header full from header all the way back magnaflow 2.25, short shifter and exedy clutch and i have no clue where to start. I run synthetic oil and 91 octane. and i know i have a misfire in cylinder 2 I tried tuning it myself but i have now clue what im doing.
I looked at the demos but everytime i watch them they show V8s and my car doesnt have features like those cars do.. it seems like the z24's are limited to what can be dont but i may be wrong..

can anyone help

[Dr. Nopps]

The absolute first order of business is to fix that misfire. I assume you have the 2.2L engine. They like to fry injectors (sidefeed style) especially if you're stuck with ethanol blended gasolines, real fast if you experiment mixing E85 in with your gas. Find out for certain though before buying an injector for around $200 a peice! You might want to run on the factory tune untill you fix the misfire, which I would also like to know the exact cause of once you figure it out. After that's squared away I'd be more than happy to give you a few pointers at least from a beginners perspective. Always feel free to post a copy of your tune and a scan log, in your case a log recorded right when it's misfiring. Helps to adress questions that may arise if people try to help. Also did you have the misfire before you tuned, right after you tuned, or quite a little while after you tuned your car?

[imphat0260]

The absolute first order of business is to fix that misfire. I assume you have the 2.2L engine. They like to fry injectors (sidefeed style) especially if you're stuck with ethanol blended gasolines, real fast if you experiment mixing E85 in with your gas. Find out for certain though before buying an injector for around $200 a peice! You might want to run on the factory tune untill you fix the misfire, which I would also like to know the exact cause of once you figure it out. After that's squared away I'd be more than happy to give you a few pointers at least from a beginners perspective. Always feel free to post a copy of your tune and a scan log, in your case a log recorded right when it's misfiring. Helps to adress questions that may arise if people try to help. Also did you have the misfire before you tuned, right after you tuned, or quite a little while after you tuned your car?

ok...... 2001 Z24 would be an 2.4 LD9 DOHC... Top feed injectors.... Side feeds were only Pre 98 on the LN2 (2.2 OHC)... To the OP, best advice I can give you is search and read like your life depended on it. You should figure out your misfire first though. Do you have a WB?

[white Z24]

yeah its a 2.4L and i just bought the HPT i got it in on monday and i also had this misfire for quite awhile. and ill try to attach a my tune its stock still n a log..

it bogs when im in hi gear at low speeds

[white Z24]

these are the tune n log hope you can help..

oh and too every time i first start my car it smells like gas

[white Z24]

ok...... 2001 Z24 would be an 2.4 LD9 DOHC... Top feed injectors.... Side feeds were only Pre 98 on the LN2 (2.2 OHC)... To the OP, best advice I can give you is search and read like your life depended on it. You should figure out your misfire first though. Do you have a WB?

oh no i dont have a wideband. i really dont know that a wideband is all i know is that everyone ask or has one ha

[laser_racer]

Wideband reads your afr or air to fuel mix in the exhaust before the cat. You can do basic tuning like cruise and idle but wot you need wideband to make sure your not pig rich or lean.

[Dr. Nopps]

"2001 Z24 would be an 2.4 LD9 DOHC... Top feed injectors.... Side feeds were only Pre 98 on the LN2 (2.2 OHC)"


Thank you for the injector/engine info. Obviously one of my least favorite features of my car (injectors) and I wondered when they got smart enough to retire them. I don't know wheather they were looking for extra hood clearence with theese things or what. I always hated my car, (that's what originally motivated me to buy HPT) so I have done very little research on them over the years. Thanks for saving me from alot of speculation & question prodding. Only Z24 I can even remember working on is my neighbors old 2.3L

[white Z24]

thank you all for the help. i actually did some more research on the wide band i was thing on getting the aem wideband and i was even thinking on putting my brothers old injectors from is ss/sc on my z24 my stocks are 24lbs and the stock ss/sc are 36lbs. i just hope it doesnt give me to much trouble with the HPtuners.

[white Z24]

Wideband reads your afr or air to fuel mix in the exhaust before the cat. You can do basic tuning like cruise and idle but wot you need wideband to make sure your not pig rich or lean.

so does that mean i would have to install it before the cat or would it be ok to put the wideband were the O2 sensor is at? its right after the cat

[Dr. Nopps]

The pacesetter 4 into 1 on your car should have an upstream (the one before the cat) o2 sensor bung which can be used and allows easier access than the stock one, with less turbulance than stock also.

[white Z24]

The pacesetter 4 into 1 on your car should have an upstream (the one before the cat) o2 sensor bung which can be used and allows easier access than the stock one, with less turbulance than stock also.

oh yeah i didnt think about that thanks

[laser_racer]

Does the header have two o2 ports before the cat?

[white Z24]

Does the header have two o2 ports before the cat?

no not on the 2.4L there is an O2 senser on the header and right after the cat like about 6'' after cat

[white Z24]

when i do diagonostics test my O2 on my header always makes my engine light come on

[laser_racer]

You need another bung to be put in your exhaust before the cat so you can install the wideband sensor. Are you having a problem with your o2 sensor? Also have you changed your plugs and checked your gap?

[JMHZ2401]

Is your check engine light flashing?

I have found my LD9 has misfires, but not enought to trip the CEL, and not enough to affect the car. You don't feel it, and it makes the power.

[white Z24]

You need another bung to be put in your exhaust before the cat so you can install the wideband sensor. Are you having a problem with your o2 sensor? Also have you changed your plugs and checked your gap?

my plugs are brand new platinum 4's. after i had installed my header thats when my o2 sensor wouldnt read right. and i havent recived my wideband yet i should have it in by the end of the week.

[white Z24]

Is your check engine light flashing?

I have found my LD9 has misfires, but not enought to trip the CEL, and not enough to affect the car. You don't feel it, and it makes the power.

my check light doesnt flash and it rarely goes on i have to drive it for weeks and then it will finally go on. yeah i dont feel it that much some times between shifts and if im in a hi gear n trying to accurate in hi gear. other then that going a constant speed it runs great still has good power

[white Z24]

i noticed when i put my aftermark intake manifold thats when it starts to misfire so i took it off and it went away.. then months later i put it back on cuz i was gonna tune it but it started to misfire again so i took it off and figured it was a crappy manifold so. i have my stock one on now n still misfires and i dont know if i should tune it and maybe it will go away?